Fire pot



F. R. HIG'LEY June 12, 1945.

FIRE POT Filed Jan. 20, 1943 I5 Sheets-Sheet l INVENTOR. BY EPA/w zF. H/GLEY flrrakwsvs June 12, 1945. F. R. HIGLEY FIRE POT Filed Jan. 20, 1943 3 Sheets-Sheet 2 I m V .2 0m. Z

June 12, 1945. F. R. HIGLEY :s Sheets-Sheet 3 ATTOPNEYJ Patented June 12, 1945 UNITED STATES OFFICE.

' FIREPOT I Frank R. Higley; Cleveland Heights, Ohio, as-' Signor to The Bryant Heater Company, Clevel land, Ohio, alcorporation of Ohio Application January 20, 1943; SerialNo. 472,965

' 19 Claims. (01. 126-451) This invention relates"to-improvements 'in fire pots, particularly fire pots for stoves or furnaces which are constructed toaccommodate deep beds of coal or other solid fuel, more particularly 'pul verulent fuel. The application is a continuation in part of my application Serial No. 449,743, filed July 4, 1942. Reference may be had to a copending application of Eric H. Ryden and myself, Serial No. 449,744, also filed July 4, 1942, for a disclosure of an adaptation of such a fire pot to a heating furnace.

It is concededly diflicult to maintain a fire in a deep bed of finely divided fuel, for example slack, in a coking magazine type furnace such as that of application Serial No. 449,744 above referred to. The efificient operation of such a furnace also presents difiiculties. The necessary air. to support combustion passes upwardly through such a bed of fuel very slowly and in amounts which are so small that very little complete combustion takes place. In order to meet and overcome these dimculties, the present invention embodies a fire pot having on its inner wall a patternof complementary overhangs and cavities, or projectionsand depressions, such that in relation to the angle.

of repose of the fuel to be handled interconnected spaces-are provided into'which fuel will not enter, so that passages are formed having continuity for draft purposes. Because of these draft passages distributed around the wall of the fire pot, a shell of fire builds up around the perimeteroi the fuel bed. 7

One of theobjects of the'present invention therefore is the provision of a fire pot of such character that passages for air and gases are provioled andlevenl distributed along its interior walls, so that combustion will be concentrated at the perimeter of the mass of fuel and distributed throughout the perimeter adjacent the heatexchanging wall of the furnace.

Another object is the formation of these passages in such manner that they will not be clogged by pulverulent material, such as slack, sawdust, granule distiller icy-products, etc., or the ashes present at the bottom of the fire pot.

Another object is the provision of a furnace fir pot of the magazine type adapted to provide quick acceleration of the rate of combustion after a prolonged low combustion rate, for example, in

order to bring about quick heatingin the morn ins after a fire has been banked throughout'the night. 1

Another object is the provision of a lining block so designed that a quantity of the blocks may be formed into an assembly constituting a complete firepotor fire pot lining.

Another object is .the provision of a lining block of a form which shall he manufacturable in commercial quantities by known casting ormolding operations, which shall be best proportioned for commercial production and which shall'have good strength characteristics.

Other objects and features of novelty will flippear as I proceed with the description of those embodiments of the invention which, for the purposes of the present application I have illustrated in the accompanying drawings in which Fig. 1 is an elevational view looking at the internal surface of a refractory block which may be I employed as a part of a furnace or stove lining;

Figs. 2 and 3 are fragmental top and bottom plan views of a furnace lining made up of blocks like that illustrated in Fig. 1.

Figs. 4 and 5 are sectional views taken substantially on the lines 4-4 and 5-45 of Fig.2.

Fig. 6 is an'internal elevational View of a modified form of lining block.

9 direction of arrows 9- 9 of Fig. '7.

Figs. 7 and 8 are top-and bottom plan views of the same. v v I I Fig. 9 is,a side elevational View lookingin the Fig. 10 is a vertical sectional view taken stantially on the line Iii-5m of Fig. '7.

Fig. 11 is a front elevational view of an assembly of blocks which may be employed in a further modification of the invention.

Fig. 12 is a bottom plan view of the same.

Fig. 13 is a side'elevationalview of the same,

and

Fig. 14 is a diagram indicating the true slopeof a block overhang relative to theangle of repose of pulverulent fuel in a furnace embodying the invention. I

The present invention is adapted to stoves and furnaces of different horizontal cross-sections, certain of the forms disclosed herein being intended primarily for use in fire pots of circular horizontal cross-section. In Figs. 1 to 5 inclusive the internal surface of a cylindrical casing.

which maybe sheet metal, is indicated at l9. The upper end of this casing ma be connected with a dome, not shown, from whicha draft pipe may lead to a chimney, as illustrated in application Serial'No. 449,744 referred to above. Proviion is made for the introduction of solid fuel,

such as coal or slack into the fire pot from the top thereof, it being the intention that the fire pot be filled up at infrequent intervals.

The casing It! is lined with blocks which'arej.

. preferably refractory, but in some instances may be cast metal. However, when cast metal blocks are employed I may make the lining in fewer sections and may dispense with the casing 10, the sections being then bolted together to, form of themselves a rigid fire pot. In the form of the invention illustrated in Figs. 1 to inclusive, the blocks are all identical in shape and size, each block having sides beveled along vertical planes through the axis of the fire pot so that a series of blocks may be fitted together to form a lining course, the lining as a whole being made up of as many courses as may be necessary to cover the surface of the cylindrical casing ID.

The outer sides of the blocks may be flat as illustrated at II, leaving vertical passages between the casing and the lining, and at the top and bottom of each block horizontal rabbets I2 may be formed, constituting horizontal passages which connect each vertical passage with those on either side thereof.

The blocks of the lower course are intended to rest upon a ledge at the periphery of the furnace grate, the latter having provision for the flow of air upwardly therethrough and along the inner surface of the lining.

The front or inner surface of each block has deformations therein providing complementary overhangs and cavities, or protections and depressions, of such character that fluid passages are provided extending from the bottom of a course of blocks to the top thereof and connecting with similar passages in the courses below and above. In Figs. 1 to 5 inclusive there are a plurality of overhangs in each block, the overhangs recurring in a regular pattern and those of one block registering with those of adjacent blocks so that a fluid passage along the surface of one block is continued along the surface of the next adjacent block. The upper surface of each passage or groove, that is the under surface of the overhang, must have an inclination or slope which is less than the angle of re-- pose of any pulverulent material which may be contained in the fire pot, for example slack or ash. Otherwise the grooves will fill up with fuel and block the travel of air and gases along the grooves. At the same time it is important that the air paths be as short as possible in order to interpose a minimum of friction to the travel of air and gases. Consequently after determining the minimum angle of repose of fuel to be used in a given furnace I so design lining blocks that the under surface of each overhang shall have a slope which is a few degrees only less than the angle of repose, as indicated in the diagram of Fig. 14. Slope as applied herein to the undersurface of an overhang or projection is defined or determined partly by the inclination of that surface in the general direction of the sloping pattern, or in the direction of air and gas fiow, that is to say along the wall, and partly by its inclination in a direction normal to the wall. I prefer to make its inclination in the latter direction approximately zero, that is with such slight deviation from the horizontal as may be necessary to provide draft for molding purposes. This undersurface will be referred to hereinafter as non-reentrant, by which is meant of course that the surface is not undercut. Such non-reentrance makes it possible to mold the blocks economically. The passages are generally triangular in cross-section, two sides of the triangle being constituted by the groove walls and the other side by the fuel in its angle of repose.

In the preferred form of the invention illustrated in Figs. 1 to 5 inclusive each block comprises three overhangs, the high spots of which are marked l5. These overhangs are protuberances which would be four-sided except for the fact that the points are removed to constitute high spots 15 and except for the fact that molding limitations make it necessary to form a small triangular surface It or IS on the underside of each protuberance, as will be explained more in detail hereinafter.

Each of the protuberances on the left-hand side of a block has two approximately triangular surfaces l7 and is above the high spot 15 meeting in a line 19, the surface I! being completed in the next block to the left. Below the high spot 55 the protuberances on the right-hand side likewise have two approximately triangular surfaces 20 and 2! meeting in a line 22, the surface 21 being completed in the next block to the right. Below the high spot the protuberance on the left side of the block has a pair of approximately triangular surfaces 23 and 24 while those on the right-hand side have similar surfaces 25 and 26, the surfaces 23 and 26 being completed in the next block to the left and right respectively:

Surfaces 2 1 are triangular surfaces in planes perpendicular to the rear surface of the block. At their lower ends they meet small triangles 28 which are also in planes perpendicular to the rear surface of the block. On the other side of the block there are triangular surfaces 29 and 30, similar to the surfaces 2'! and 28 respectively. All of the surfaces are formed in the manner stated in order to meet molding limitations, as will be further described hereinafter. It will be noted that the three high spots l5 lie in a common plane parallel to the rear surface of the block.

The sides of the blocks have beveled surfaces 3| formed along radial planes through the axis of the fire pot. Since each block subtends an arc of 30 twelve blocks are required to complete a course. The blocks of each course are staggered with respect to those of the next course above or below. The surfaces 24 and 25 in the middle of the block and one of each of the surfaces l8 and 2G in the middle of the block are complete. The other surfaces are partial, being completed in adjacent blocks of the same course or in blocks of the courses above or below. Surfaces 2! on the left-hand portion of the block of Fig. l are so marked because they match with surfaces 2! on the right-hand side of an adjacent block, and surfaces IT on the right-hand side of the block are so marked because they match with surfaces 11 of the next adjacent block.

Air and gases may proceed upwardly in a helical direction, as by following the grooves formed.

under the surfaces 25 and 23 and continuations thereof, or they may proceed upwardly in a zigzag path as by following the grooves formed beneath the surfaces 25, 24, 25 etc. As a matter of fact, they follow both paths. It will be appreciated that the blocks may be constructed with shorter or longer vertical dimensions than that illustrated. If of a shorter dimension, each block would have two instead of three protuberances. If longer it could have four or any greater number of protuberances, When the blocks have an odd number of protuberances they are laid in staggered relation, and when they have an even number they are laid in alignment vertically. It will also be appreciated that the protuberances may be located in themiddle of the blocks rather than toward the sides thereof,'the

middle'location requiring certain minor'changes in the contour of the protuberance's in order to make them moldable. The radial angle of repose of fuel is indicated in Figs. 4 and15 by the broken lines 32,'and the spaces 33 between those lines and the groove walls indicate thecrosssectional areas at those'points of the air and gas paths. The cross-sectional .area of each groove decreases from its lower end toward its upper end, but as the air and gases approach the small end ofthe groove they come under the next higher overhang and thus enter the large end of another'groove.

In Figs. 6 to .10 inclusive I have illustrated a form. of the invention in which each block subtends an angle of 60, thus requiringbut six blocks to a course. Eachblock in this case has two .protuberances and the blocks are laid in alignment vertically. The high spots of the protuberances are marked 35 and 3t. Beneath these high spots there are approximately horizontal triangular surfaces 31 and 38 of small extent. Above the high spots 35 and 36 on the inner wall of the block there are surfaces 39 and 4f! which incline upwardlyiand outwardly from, those points. Beneath the high spot.35 on opposite sides of the triangle 3? there are surfaces 4| and Mconstituting the upper surfaces of inclined grooves. Similarly; beneath high spot 36 and on opposite sides of triangle there are surfaces 43 and 44 constituting the upper sides.

-43 in the middle of the blockandthe triangles 3'! and 38 are complete. 'None of the othersur: faces are complete in one block. I They; continue in the blocks on either side or above and below, two surfaces atthe left side of the block being marked 40' because they are continuations 'of the surfaces 46 in the next block to the left, and a surface at the right side of the block being The surfaces 45, 41 together'constitute aoconr tinuation of the-surface of an adjacent block,

and. the surfaces 46, 48 together constitute a continuation of the surface 4! of an adjacent block. a a

The rear of the block may comprise a flat surface 49 and two curved surfaces 50 and 51,

second form they are marked'L. noted that the high spots 'of the blocks are located at points other" than the corners of the blocks, the corners being points of intermediate height. This has a practical advantage of some.

In molding a. block according to either of the forms-of the invention thus far described-I the marked 39' because it constitutes a. continuation of the surface 3910f the block next to the rightthe latter being adapted to fit against the inner ances are at the same radial distance from the I casing 52 as well as at the same perpendicular distance from the rear surface 49 of the block,

and that the lines formed, at the intersections of surfaces 39 and 4| on the one hand and surfaces Ml and 44-011 the other hand are in the same plane parallel to the rear surface of the block. This latter characteristic has advantages from a practical standpoint. In the first form of the invention the low spots die is withdrawn in adirection perpendicularto the rear surface of the block.. If thesurface N,

for example, were caused'to conform to the intersection between the surface 23 and.,a generally vertical radial plane through the'xhigh spot IS, the surface 24 would be undercutj Such an undercut might in some cases be desirable as increasing the cross-sectional-area of the passage beneath it; but it is not practical for the reason that it fcannot be molded, In order to avoid undercutting of surface 24, I make that surface substantially perpendicular to the rear surface of the block and join it with the surface 23 by the small triangular surface iii-whichis also perpendicular to the rear surface of the block. Similarly and for the same reason, surfaces 25, 21 and 29 in thisform of the. invention are madeperpendicular, to the rear surface of the block and meet smalltriangular surfaces |6;;28 and 30, respectively. In the second form of the invention, undercutting is avoided i by making the surfaces 42, 43,45 and'46 perpen-- dicular to therear surface-l9 and causing them to meet small triangular surfaces 3?, 38, ti and 48 respectively, which the rear surface. I Of course in molded blocks draft must be proare also perpendicular to vided, but for the sake of simplicity I have ignored.

In Figs. ll, 12 and 13 1 have illustrated a third formof the invention, wherein each block has a single protuberance. Although shown in a form adapted for application to a rectangular fire pot, it is capable of application to a cylindri cal one with minor changes in design. In print ciple the construction is thesame as in the pre- -viously described forms of the invention. The

pathsfor air or other gas flow are crossed and inclined or zigzag. 1'

Each block has asingle high spot 55 at the base of ,a ridge 56 alongthe vertical center line of the block. The blocks vare diamond-shaped with blunted ends 57. The surfaces .58 and 59 on either side of the ridge .56 slope away from the high .spot, 55, and the two upper edges. fill and El of each block are at a uniform lowlevel. From the lower edges 62 and 630i the'surfaces 53 and 59, respectively, there extend rearwardly surfaces 64 and 65 which are perpendicular to the flat rear surface 66 of the block. When the blocksare assembled thelow spots markedL are all over-' hung by high spots 50 of the blocks next. above;

and the resulting cavities 01' grooves provide 'ade- 7 overhung by a high spotare markedL. In the It-will' be i quate paths for the travel of air and gases'upwardly in inclined or zigzag paths.

The present invention provides a multiplicity of air passages of crossing'or zigzag form, which become crossed helices if the magazine is cylindrical, these passages being evenly distributed throughout the perimeter of the fire pot.

In operation, when a damper controlling the flow of air to the space below the furnace grate is open, air fiows up into these various draft passages. This results in a concentration of combustion at the perimeter of the fire pot with distribution over the inner wall surface thereof, and this combustion proceeds even though the fuel be so finely divided and closely compacted as to prevent the passage of air through the body of the fuel bed. The fuel at the bottom of the fire pot also burns of course, the products of combustion therefrom flowing radially outward and then upwardly through the passages distributed along the inner wall of the fire pot. As the fuel bed thus burns away, the weight of the unburned mass causes the whole body of fuel to descend. In the case of coking fuel, the fuel bed forms a solid core of coke which may remain suspended until it burns peripherally free from the support which it receives from the encircling wall, at which time the whole mass falls, jarring loose ashes and forcing them through the grate. The furnace is thus to a considerable extent self-clearing. Thereafter the bed of fuel continues to burn upwardly and inwardly from the bottom and sides respectively.

As previously stated the term "slope as herein used, relates to the inclination of the under surfaceor under surfaces of the overhangs or projections by which the passages are overshadowed against the flow of fuel. While each individual increment or portion of these under surfaces may be considered to be planar and to have in reality a single inclination or slope, it is convenient to consider such inclination intwo distinct directions, that is to say in the direction toward the face of the fire pot and in the direction along the face of the fire pot, these two inclinations together determining the absolute slope of the planar increment. The projections or overhangs may be said to cast shadows, considered with respect to the direction of flow of fuel, and thereby to define grooves or passages. For example each projection may be said to cast a shadow against the flow of fuel toward the face of the fire pot. It is not enough, however, in order to keep the passages from filling up, to prevent fiow of fuel toward the face of the fire pot. On the contrary fuel flowing along the face, and in every directionbetween that and the radial direction, must be prevented from entering the passages. A lining built in accordance with the invention for a furnace intended to handle coal in any form including slack should comprise lining blocks having deformations, the under surfaces of which have a slope along the wall or face of the fire pot of the order of the angle of repose of such fuel being of the order of This difference between the slope angle and the angle of repose has been found by experience to afford a sufficient margin of safety to insure clear air passages. Of course the transverse or radial inclination of such under surface must be less than 35 also, but, as previously stated, I so design the blocks as to provide a slope to said under surface in a direction toward the face of the fire pot only slightly greater than zero in order that the cross-sectional area of the groove may be as great as molding limitations will permit.

The blocks of the two forms shown in Figs. 1 to 10 inclusive are so designed as to provide maximum content within the dimensions of rectangular solids f commercially accepted sizes, the blocks therefore having optimum qualities of strength and low cost in addition to the provision of adequate draft passages on their faces.

All forms of the blocks herein disclosed may be used in either an up draft or a down draft furnace, it being desirable also that the draft passages extend throughout the length of the fire pot from bottom to top thereof or vice versa.

Having thus described my invention, I claim:

1. A fire pot for solid fuel, having deformations on its inner face, each deformation comprising an overhang having a non-reentrant undersurface disposed to set up an inclined compleinentary cavity between said face and the fuel bed, and for that purpose said undersurface having slope which in-every direction is less than the angle of repose of the fuel. a

2. A fire pot for solid fuel, having deformations on its inner face, each deformation comprising an overhang having a non-reentrant undersurface disposed to set up an inclined complementary cavity between said face and the fuel bed, and for that purpose said undersurface having slope less than the angle of repose of the fuel both along said face and normal to said face.

3. A fire pot for solid fuel, having deformations on its inner face, each deformation comprising an overhang having a non-reentrant undersurface disposed to set up a complementary cavity between said face and the fuel bed, and for that purpose said undersurface having slope less than the angle of repose of the fuel both along said face and normal to said face, each of said deformations other than those at the lowermost level being disposed on said face to overhang the upper end of a cavity formed by a subjacent deformation to provide upwardly leading continuity of said cavities, whereby draft passages are provided contiguous to said fuel.

4. A fire pot for solid fuel, having protuberances on its inner face arranged in a sloping pattern, each said protuberance comprising an overhang having a non-reentrant undersurface disposed to set up a complementary cavity between said face and the fuel bed, and for that purpose said undersurface having slope less than the angle of repose of the fuel both along said face and normal to said face, and each of said protuberances other than those at the lowermost level being disposed on said face to overhang the upper end of a cavity formed by a subjacent protuberance to provide upwardly leading continuity of cavities from one to the next, whereby draft passages are provided contiguous to said fuel.

5. A fire pot comprising one or more courses of identical blocks arranged to surround and contain a bed of solid fuel, said blocks having deformations on their inner faces, each said deformation comprising an overhang having a non-reentrant undersurface disposed to set up a complementary cavity between said face and the fuel bed, and for that purpose said undersurface having slope less than the angle of repose of the fuel both along said face and normal to said face.

6. The construction defined in the preceding claim, characterized by the fact that the deformation of each block comprises an overhang positioned midway between the lateral extremities of the block, and the blocks of one coursebeing staggered with respect to those .of the course next above or below.

7. A fire pot for solid fuel, circular in horizontal section having deformations on its inner face arranged in a generally helical pattern, each deformation comprising an overhang having a non-reentrant undersurface disposed to set up a complementary cavity between said face and the fuel bed, and for that purpose said undersurface having slope less than the angle of repose of the fuel both radially and along said face,

8. A fire pot for solid fuel, .having deformations on its inner face comprising protuberances in a recurrent pattern, each of said protuberances comprising an overhang having a plurality of non-reentrant undersurfaces disposed to set up complementary cavities between said face and the fuel bed, two of said undersurfaces diverging upwardly toward the protuberances next above,

the slope of said last named undersurfaces along said face and normal to said face being less than the angle of repose of said fuel, and each of said protuberances other than those at the lowermost level being disposed on said face to-overhang the upper ends of cavities formed by two subjacent protuberances to establish continuity of cavities in oppositely inclined directions, whereby intercommunicating inclined draft passages are provided.

9. A fire pot for solid fuel, having deformations on its inner face, each deformation comprising an overhang having an undersurface disposed to set up an inclined complementary cavity between said face and the fuel bed, and for that purpose said undersurface having slope along said face less than the angle of repose of the fuel and slope in a direction normal-to said face which is between zero and an angle less than the angle of repose of the fuel. l

0. In a cylindricalfire pot, a lining provided with recurrent deformations constituting overhangs, said lining comprising a plurality of identical moldable blocks each carrying a plurality of said deformations, the deformations in each block being centered about points on opposite sides of the axial plane through the middle of the block, said overhangs on their inner side's having non-reentrant undersurfaces to permit molding of the block including withdrawing movement of the forming die in a direction parallel to said axial plane, while maintaining the extremities of tical-plane through the chord of said are whereby undercut surfaces are avoided.

13. A block for use in building up the lining of a-cylindrical firepot of which said block is adapted to subtend a given arc, an overhang located on a center to one side of the axial plane through the middle of the block, the under surfaces of said overhang comprising two faces lying substantially in planes at right angles to the vertical plane through the chord of said are and meeting ina line substantially perpendicular to the said vertical plane; I

' 14. A block for use in building up the lining of a cylindricalfirepot of which said block is adapted to subtend agiven arc, an overhang located on a center to one side of the axial plane through the middle of the block, the side surfaces of said overhang diverging upwardly and outwardly to-.

ward the side walls of the block, said overhang having a triangular under face lying in a plane substantially perpendicular to the vertical plane through the chord of said arc, said side surfaces conforming. substantially with planes perpendicular to the said vertical plane.

15. A refractory block'for use building up the lining of a cylindrical firepot of which said block is adapted to subtend a given arc, said block having inwardly extending deformations characterized by complementary overhangs and cavities for facilitating thefiow of air or gases upwardly along the inner surface of the block, the undersurfaces of said overhangs having slope which in any given direction is less than the angle of repose of the fuel, and the inner extremities of said recurrent deformations lying in a common plane parallel to the chord of said are.

16. A refractory block for use in building up the lining of a cylindrical fire pot, said block having ing a top surface and side surfaces, the side surside walls adapted to conform with radial planes through the axis of the fire pot, an overhang on v the forward face of the block, said overhang havfaces of said overhang diverging upwardly and outwardly and the intersection of the top sur- I face of the overhang with one of said side surfaces defining a line parallel to the vertical plane through-the chord of the angle between said rathe overhangs in a regular pattern in" the fire pot,

each of said under surfaces having slope which in any direction is less than the angle of repose of the fuel.

11. A fire pot having on its inner face a protuberance projecting inwardly, furthest at the middle of its bottom extremity and a decreasingly less amount laterally and upwardly from said extremity, said protuberance having under surfaces, diverging upwardly from said extremity with less slope than the angle of repose of the fuel to be handled, and diminishing in width as they'diverge, said surfaces also having slope normal to said face less than said angle of repose.

12. A block for use in building up the lining of a cylindrical firepot of which said block is adapted to subtend a given arc, an overhang located on a center to one side of the axial plane through the middle of the block, the under surfaces of said overhang comprising two faces meeting at the extremity of the overhang, said two faces lying substantially in planes at right angles to the verdial planes.

17. A block for use in building up the lining of a fire pot, having-its high point at the bottom of its central vertical plane adapted to form an overhang, said overhang having upwardly and outwardly diverging under surfaces.

18. A refractory block for use in building up the lining of a fire pot, said block being approximately diamond-shaped, having its high point at its lower corner constituting an overhang with a low point at its upper corner, whereby when a series of blocks are assembled in .a fire pot with the blocks of successive courses in staggered relation and the fire pot is filled with pulverulent material, crossed, inclined gas passages are set up alongthe surface of the fire pot.

19. A refractory block for use in building up the lining-"of a cylindrical magazine fire pot, having in its front face deformations crossing. the

FRANK R. HIGLEY. A 

